Greenhouse calendar - May
Spring sunshine will be warming up the soil nicely, but nights can still be chilly and frost is still a possibility. Make sure plants are hardened off before planting out, keep tender plants under cover for a couple more weeks and have fleece at the ready.
In the garden:
- Sow every 3–4 weeks fast-growing crops like radish and salad leaves so that you have a regular supply.
- Gradually harden off plants that have been growing in a greenhouse or on a windowsill, acclimatising them to cooler weather, wind and rain by moving them outdoors during the day for at least a week and moving them back under cover at night. Then leave them out in a sheltered spot over night for a few days before planting out into their final homes.
- Check spring-flowering members of the lily family, such as snake’s head fritillaries, for scarlet lily beetles and their eggs.
- Deadhead daffodils as the flowers fade to prevent them expending energy on forming seed pods, but leave the foliage to die back naturally as this will feed the bulbs and produce better flowers next spring.
- Plant hanging baskets and containers with summer bedding once the danger of frost has passed.
- During dry spells keep plants you’ve recently planted well-watered.
In the greenhouse:
- Sow indoors this month tender vegetables such as sweetcorn, courgettes, squashes, French beans and runner beans.
- Ventilate the greenhouse on sunny days to prevent the temperature from getting too high.